Between June 2012 and October 2014, direct policing costs were 7.3 million pounds with 1.8 million pounds spent on overtime, BBC cited the police as saying.

Assange, who denies allegations that he sexually assaulted two women in Sweden, faces arrest if he leaves the embassy.

Wikileaks founder Julian Assange. Pic/AFP

A Wikileaks spokesperson said the policing costs were "embarrassing".

Scotland Yard confirmed the cost of the operation to British taxpayers in the first 28 months, until Oct 31 last year, reached 9 million pounds.

The cost of a further three months policing is now expected to have taken the total bill to about 10 million pounds.

"It is embarrassing to see the UK government spending more on surveillance and detaining an uncharged political refugee than on its investigation into the Iraq war, which killed hundreds of thousands," WikiLeaks spokesperson Kristinn Hrafnsson said.

Assange attacked Sweden, saying the country adopted the "shameful legal practice" of "indefinite detention without charge".

British courts have repeatedly ruled that he should be extradited to Sweden to face questioning.

But Assange fears he could be extradited to the US to face charges over the release of top secret documents by Wikileaks.

He entered the embassy after the British Supreme Court dismissed his bid to reopen his appeal against extradition.

He was then granted asylum by Ecuador in August 2012.

He has been warned he would be arrested if he left the embassy, prompting the 24-hour guard by Metropolitan Police officers.